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    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
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<body>
    <script>
        //求两个数之间和（包括两个和本身）
        function sum(a,b){
            var sum = 0;
            for(var i = a;i<=b;i++){
                sum += i;
            }
            console.log(sum);
        }
        sum(1,5);
    </script>
</body>
</html>